glitches in texture in blender texture drowing
Painting


If the model is only one color directly you can assign the material.
You can paint the model directly with different colors.  You may need to twist and turn the model so the faces of  little nooks and crannies (small tight spaces) are directly facing you the painter.  You can hide parts of the 3D Mesh so that the tight spaces are more obviously accessible.
You may paint on the texture directly to fill in the holes.  Enter paint mode for the texture and paint directly to fill in holes.